1. Field of the Invention
The present invention generally relates to a low profile electrical connector for interconnecting two printed circuit boards, and particularly to a high speed, high density connector having enhanced structure for insuring a reliable signal transmission.
2. Description of Related Art
Continued advances in the design of electronic devices for data processing and communications systems have placed rigorous demands on the design of electrical connectors. Specifically, electrical connectors having higher densities and pin counts require careful consideration of the problems which result from decreasing the distance between contacts. Understandably, greater density cannot sacrifice electrical or mechanical performance of a connector.
A difficulty in designing high density connectors having a low-mated height is in maintaining proper alignment of the contact elements of engaged connectors so as to insure reliable electrical connections therebetween. U.S. Pat. Nos. 6,042,389, 6,093,035, 6,471,526, and 6,558,170, issued to Lemke et al. and Harper, disclose high-density, high-speed, board-to-board connectors. These connectors have a respective receptacle and a respective plug. The receptacle includes a receptacle housing receiving therein a number of receptacle contacts coupled to a first substrate, while the plug includes a plug housing receiving therein a number of plug contacts coupled to a second substrate and establishing electrical connection with receptacle contacts of the receptacle. However, the problem to maintain proper alignment of contacts during mating procedure is not solved and no particular enhanced structure is provided to insure a reliable electrical connection from the first substrate to the second substrate.
With the increased demands for miniaturization of the data processing and communication systems, another design problem resulting from high density, low-mated height connectors is that the tiny, slender contact elements are susceptible to damage if used improperly. U.S. Pat. Nos. 6,471,526 and 6,558,170 disclose two-beam contacts resided within apertures of the housing. The contacts have upper arms flexibly connected to tail portions. Upper arms have a converging section and an outwardly diverging lead-in section. As plug and receptacle mate, upper portions of plug contacts flexibly engage upper arms of receptacle contacts, which accept upper portions of the plug contacts into outwardly diverging lead-in sections. Referring particularly to figures of the cited patents, it is easy to see that the upper arms of the receptacle contacts extend beyond a relatively large distance from a mating face of the receptacle. When engaging with the plug, the receptacle contacts will be liable to deformation for flexibility. On the other hand, it brings difficulties to align the plug contact with the receptacle contacts thereby effecting reliablity of electrical connections therebetween. If one or more of the receptacle beams are out of position, it is very easy for the corresponding plug blades to fail to mate properly.
Hence, a low profile electrical connector with high density and excellent contact stability is highly desired.